U.S. Pat. Nos. 4,583,749 Hatch and 4,664,392 Hatch, which are assigned to the assignee of the present invention, disclose a seal assembly including a polytetrafluoroethylene (PTFE) seal that is utilized with a vehicle air conditioning compressor. Such air conditioning compressors conventionally include a rotary shaft which extends outwardly from a refrigerant chamber that is enclosed by the seal about the shaft to maintain refrigerant and lubricating oil within the chamber. This shaft permits rotary driving of the compressor for its operation. In certain environments such as off the road vehicles or other vehicles subjected to atmosphere having dust and other debris circulating within the air, the seals can abrade during use due to the debris which enters the seal assembly between the seal and the shaft. Prior seal assemblies developed to overcome this problem have included dust excluders that engage the shaft on the opposite side of the seal from the refrigerant chamber; however, this type of combined seal and dust excluder does not permit the seal assembly to be manufactured and sold without the dust excluder when the vehicle is not to be used in an environment that necessitates the dust excluder. Also, the seal and dust excluder of such a conventional design both engage the air compressor shaft at adjacent axial locations which can produce an undesirable heat buildup in the shaft.
Other seals and assemblies which have general utility or utility other than with vehicle air conditioning compressors so as not to be applicable to the present invention are disclosed by U.S. Pat. Nos. 2,272,650 von Veh; 3,320,006 Cozzarin; Re 31,058 Povejsil; and 4,465,285 Toyoda et al.